administered. >> pelley: seth, thank you. dr. jon lapook is our medical correspondent. john, seth just said the c.d.c. is investigating how the vials were contaminated. how might they have been wentaminated? haat are the possibilities? >> reporter: scott, that medication is supposed to be prepared in a sterile environment but if there's a breakdown in the system there could be contamination in the fungus. it's common in soil, decomposing leaves and even floating in the air. >> pelley: if the fungus is everywhere, as you describe it, why is it so dangerous in this case? >> reporter: in somebody with a normal immune system the lungs filter it out. ouen you inject it directly into the spine, that's like a straight highway to the brain. >> pelley: jon, thank you very ver. it has been more than three weeks since that deadly terrorist attack on the u.s. s.nsulate in benghazi, libya. today, the libyan government finally allowed a team of f.b.i. agents to see the crime scene. four americans were killed in that attack, of course, including ambassador chris stephens. the agents, with a u.s. military
